In order to meet an ever-increasing demand for wireless data traffic, wireless communication systems are developing to support a higher data transmission rate. The 4th generation (4G) system, which is starting to be commercialized, has been developed mainly to improve spectral efficiency in order to increase a data transmission rate. However, it has become difficult to satisfy an explosively-increasing demand for wireless data traffic solely by the spectral efficiency improvement technology.
To address the above issue, there is a method for using a very wide frequency band. A frequency band used in the current mobile cellular system is generally lower than 10 GHz, and it is very difficult to secure a wide frequency band. Therefore, there is a need to secure broadband frequencies in a higher frequency band.
However, as an operation frequency band for wireless communication becomes higher, a propagation path loss increases. Thus, a wave propagation distance decreases, and a service coverage decreases accordingly. Beamforming is a technology for addressing this issue, that is, for reducing a propagation path loss and increasing a wave propagation distance.
Beamforming includes transmission beamforming performed in a transmitter and reception beamforming performed in a receiver. The transmission beamforming concentrates a wave propagation region in a specific direction by using a plurality of antennas. Herein, a group of a plurality of antennas may be referred to as an antenna array, and each antenna included in the antenna array may be referred to as an array element.
When transmission beamforming is used, a signal transmission distance is increased and a signal is hardly transmitted in directions apart from a corresponding direction. Therefore, an interference with respect to a neighboring cell is greatly reduced.
Meanwhile, the reception beamforming uses an antenna array in a receiver, and concentrates a wave reception-possible region in a specific direction to increase a reception distance of a signal. The reception beamforming excludes a signal received in other directions than a corresponding direction from reception signals to provide a gain of blocking an interference signal.
In a wireless communication system using either the transmission beamforming or the reception beamforming, an absolute amount of a neighboring cell interference is reduced, such that the use of one or more additional beams in a corresponding cell becomes possible. As such, a technique for increasing a transmission capacity by simultaneously transmitting or receiving one or more beams in different directions in one cell or base station is referred to as spatial/space division multiple access (SDMA).
When beamforming and SDMA are used, an uplink power control method needs to differ from an uplink power control method used in previous cellular environments but in the related art, there is no uplink power control method suitable for a wireless communication system using beamforming and SDMA.
Therefore, a need exists for a method and an apparatus in which a mobile terminal transmits a signal by controlling an uplink transmission power based on neighboring reception beam allocation information in a wireless communication system using beamforming.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.